<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style type="text/css">
    .box {
        /*border-top: red solid 10px;*/
        border: red solid 10px;
        width: 300px;
        height: 100px;
    }

    table {
        border: 5px solid green;
        border-collapse: collapse;
    }

    td {
        border: 1px red solid;
    }

    .username {
        width: 100px;
        height: 30px;
        /*border: 0 none;*/
        /*outline-style: none;*/
        background: #fff;

    }

    .username:focus {
        background: red;
    }

    .username:hover {
        background: red;
        border: 1px dashed blue;
    }

    input[type=text][username] {
        width: 300px;
        height: 100px;
        background: red;
    }
</style>
<body>
<div class="box">

</div>
<table>
    <tr>
        <td>语文</td>
        <td>数学</td>
        <td>英语</td>
        <td>政治</td>
        <td>地理</td>
    </tr>
    <tr>
        <td>语文</td>
        <td>数学</td>
        <td>英语</td>
        <td>政治</td>
        <td>地理</td>
    </tr>
</table>
<label>用户名：</label>
<input type="text" class="username"/><br/>
<label>密码：</label>
<input type="password" class="passowrd"/><br/>
<label>邮箱：</label>
<input type="text" class="email"/><br/>
</body>
</html>